Prefabricated buildings have gained widespread acceptance as a result of their reduced fabrication costs. These prefabricated buildings commonly have a building framework with spaced apart upstanding side beams and roof beams between which are connected a plurality of generally horizontally extending support members. These horizontally extending support members are commonly known as girts when they are located in the side walls of the building and purlins when they are located in the roof of the building. These support members have exterior covering panels attached thereto to provide the exterior covering of the building. There are two different systems in general use today to attach the exterior cover panels to the girts and purlins of the buildings.
One of these systems allows the fasteners attaching the cover panels to the support members to be located inside the building. This system uses cover panels equipped with side flanges spaced inboard of the exterior section of the cover panels. The side flanges are positioned so that the side flanges of adjacent cover panels can be overlapped and attached to the support member as a unit. Because these side flanges are spaced inboard of the exterior section of the cover panels, the fasteners attaching these panels to the support member are thus located inside the building. This, of course, reduces corrosion since the fasteners are not exposed to the outside environment. In order to use this system, holes are prepunched through the side flanges on the cover panels and through the support members to which the cover panels are to be attached prior to the erection of the building. The panels are positioned so that the holes in the overlapping side flanges are aligned with each other and also aligned with the appropriate hole in the support member so that a bolt can be inserted through the aligned holes and a nut screwed thereon to attach the cover panels to the support member through the overlapping side flanges. One of the problems experienced with this system is that special machinery is required to prepunch the holes through the support members and through the side flanges on the cover panels. Another problem associated with this system is that it is difficult to locate the holes in the side flanges on the cover panels and the support members with sufficient accuracy to insure that the prepunched holes can be aligned during the erection of the building.
The other system in general use today uses cover panels whose edges are overlapped and attached to the support members by installing a fastener from the exterior of the building through the cover panels into the support member. Because it is difficult to determine the location of the support members from the outside of the building once the cover panels are positioned for installation, holes are typically pre-drilled through the cover panels at locations which can be placed in registration with the support members when the cover panels are positioned on the building. The workman then aligns the pre-drilled holes in the cover panels with the support member and typically used self drilling and self-tapping fasteners to form a hole through the support member using the pre-drilled holes in the cover panels as a guide and then screws the fastener into the support member to lock the cover panel onto the support member. One of the disadvantages associated with this system is that it required the pre-drilling of the holes through the cover panel prior to positioning on the building and required that these pre-drilled holes be located with sufficient accuracy to be aligned with the support members once the cover panels are in position. This has created problems in that the support members are not always located with sufficient accuracy to insure that location of the pre-drilled holes on a standard dimension will cause the pre-drilled holes to always be in registration with the support members. Another problem, of course, is that the head of the fastener is exposed to the exterior environment thereby requiring special techniques to reduce the corrosion of the fastener.